Method for producing (meth)acrylic acid esters

Abstract

The invention relates to a method for producing (meth)acrylic acid esters by transesterification of the (meth)acrylic acid with an alkanol in the presence of an acid catalyst, a polymerization inhibitor and an organic solvent that forms an azeotropic mixture with water. The reaction mixture is heated to the boiling point of the mixture in a reactor that comprises a distillation unit with a column and a condenser. The azeotropic mixture is distilled off, the organic solvent is returned to the column as reflux and at least a part of the column reflux is contacted with copper or a copper-containing material. The inventive method is advantageous in that substantially no polymerizate is produced in the distillation column.

We claim:  
     
         1 . A process for the preparation of (meth)acrylates by esterifying (meth)acrylic acid with an alkanol in the presence of at least one acidic catalyst, at least one polymerization inhibitor and an organic solvent which forms an azeotropic mixture with water, with heating in a reactor having a distillation unit, which comprises a column and a condenser, to the boiling point of the reaction mixture, wherein the azeotropic mixture is distilled off, the organic solvent is recycled as reflux to the column and at least some of the column reflux is brought into contact with copper or with a copper-containing material.  
     
     
         2 . A process as claimed in  claim 1 , wherein at least some of the internals having a separation effect or of the packing of the distillation column consist of copper or of a copper-containing material or are coated therewith.  
     
     
         3 . A process as claimed in  claim 1  or  2 , wherein a packed column which contains copper packings in the upper region is used.  
     
     
         4 . A process as claimed in any of the preceding claims, wherein an alkanol which gives a (meth)acrylate having a molecular weight of >200 is used.  
     
     
         5 . A process as claimed in  claim 4 , wherein the alkanol is selected from lauryl alcohol, stearyl alcohol, tert-butylcyclohexanol, ethyldiglycol, cyclic trimethylolpropane formal, 1,6-hexanediol, a polyethylene or polypropylene glycol or a C 1 -C 4 -monoalkyl ether thereof, glycerol, trimethylolpropane, pentaerythritol and the ethoxylated and/or propoxylated compounds thereof.